Setup PDF.js web viewer from its github repository

init_pdf.js.sh

# configs
JS_DIR=static/js/vendor/pdf.js
CSS_DIR=static/css/vendor/pdf.js

echo "[INFO] Clone https://github.com/mozilla/pdf.js into 'temp'"
git clone -b gh-pages https://github.com/mozilla/pdf.js temp

echo "[INFO] Init pdf.js directories"
rm -rf $JS_DIR
rm -rf $CSS_DIR
mkdir -p $JS_DIR
mkdir -p $CSS_DIR

echo "[INFO] Copy resource files to 'static' folder"
cp temp/web/viewer.css $CSS_DIR
cp -R temp/web/images $CSS_DIR

cp temp/web/compatibility.js $JS_DIR
cp temp/web/l10n.js $JS_DIR
cp temp/web/viewer.js $JS_DIR
cp temp/build/pdf.* $JS_DIR

cp -R temp/web $JS_DIR
cp -R temp/web/locale $JS_DIR
cp -R temp/web/cmaps $JS_DIR

echo "[INFO] Modify configs"
sed -i '' "s@../build/pdf.worker.js@static/js/vendor/pdf.js/pdf.worker.js@" $JS_DIR/viewer.js
sed -i '' "s@../web/cmaps/@static/js/vendor/pdf.js/cmaps@" $JS_DIR/viewer.js
sed -i '' "s@compressed.tracemonkey-pldi-09.pdf@@" $JS_DIR/viewer.js

echo "[INFO] Clear 'temp' directory"
rm -rf temp

echo "[INFO] Success"

Create your viewer.html from https://github.com/mozilla/pdf.js/blob/gh-pages/web/viewer.html with new static resource's urls and your custom UI.